Electric resistance element.



A. L. MARSH.- v ELECTRIC RESISTANCE ELEMENT.

APPLICATION I' ILED I'BB. 18, 1007.

l inary;

flaemiz, jfzmga dzm moizfiiyfl PATENTED JULY 9, 1907.

' sista-nce material, a metal ALBERT'LMXRSH, OFA-LAKE BLUFF,

T0 ollrohom it may of its manganese increase the electrical STAT-ES PATENT, OFFICE.

ILLINOIS, AssIeNoR' TO THE HOSKINS COMPANY, or

' CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.-

.nnscrnro'ansrsrarrcs Emma's Be it known that I, Annam- L. Manon, accitizeirof the United States, residing at Lake Bluff, in the county- 'of lake and Stateof Illinois, have invented a new and useful Improvement in Electric Resistance Elements, of which the following is a specification. My object is provide, as an improved electric rewhich has the property of being particularly low in electric conductivity, has a melting point exceeding, that of pure copper, and may be drawn or otherwise shaped to form particularly durable, eflicient, and desirablestrips, strands, or filaments suitable for use in the. various connections where. electric resistances are desirable.

'I have discovered'that when comparatively: small proportions of certain metals having refractory oxids are added to nickel or cobalt, or to either of these metals alloyed with a metal of the chromium group, as delined in Letters.Patent.No.v 811,859, grantedto me Feb. 6, 1906, the durability under high temperatures of the alloy so produced is augmented. For example,

sp alloy of nickel and chromium containing aboutffe'n per cent. chromium, when heated, in the atmosphere, to a white heat, becomes coated with a black oxid; and that when about four per cent. 0? aluminium is added to this alloy, the scale so formed-"is tougher and more adherent and affords a better pro-' tection against further or destructive oxidation than I afforded by the black-oxid of the first mentioned or m'mpl'e alloy. A wire of the alloy containing aluminium has'been heated to incandescence'at a temperature so high as to actually melt the metal or core within the film or shell of oxide formed under lowertemperature upon the wire, core against further or destructiveoxidation, by reason to'ugh or.coherent properties, which it intact.

.While such metals as aluminium, tin, silicon, and resistance of nickel, or nickel alloyed with a metal of the chromium group, their principal advantage coniets in the deoxidizing action they exert on the metal or alloy to which they are added and the protecting property of the'oxid film formed fiom the alloy; though nickel. containing about three per cent. aluminium'has a resistance of about .53 ohms per foot of wire of .40 mm. diameter, whereas the 'lickel from which the I! only about .21} ohms so tilt the addition of doubles the A very good alloy for a resistance element having the property set forth, and one which may be rolled 'or drawn into'wire, is composed of sdout eighty-eight percent. nickel, about eight per chromium and about four per cent. slloydrawnintowire indismeteshsssreper foot of wire or like diameter,

Specification Letters Patent. 7 Application m February 18. 001.

' l200 0., or higher..'

' Patented July 9, 1907. sol-mm. 868,004.

sistance of about 2.2 ohms per foot, which is about fifty times that of pure copper. Moreover the increases the melting point of the metal.

The accompanying drawing shows a rheostat of well-' known type, in which the coiled wires 1 are resistance elements formed of a metal alloy, consisting of eightyeight per cent. nickel, eight per cent. chromium and fourper cent. aluminium.

Though, so far as I am at present aware, aluminium is the most desirable metal for my purpose, as an addition-to nickel or its alloys, my invention is intended to include any metal more electropositive than nickel and having a" refractory oxid wi melting point of Im aware that aluminium, manganese, silicon and other metals have hitherto been added to nickel and other metals to produce sound castings/but, it was hithero unknown that the resultant alloys would produce electric resistance elements having the surface oxidizing property with the protecting advantage 1 hereinbefore explained.

Eithernickel, or cobalt which has similar. properties, is suitable for my purpose when alloyed with aluminium in', substantially, the proportions specified, or 30 with any metal herein referred to as the equivalent of aluminium, with or without the member of the chro-' mium group as an element of the alloy. Where I mention in the appended claims a metal having the properties o(nicke1 or cobalt, I wish to designate only which effectively protected the alloy'wss made has a resistance the three per cent. aluminium the metals nickeland cobalt, which have properties that are the same for my purpose, but which cannot both be classed under any single term' of which I am aware. I

What I claim as new,

Patent 'is- 1. An electric resistance element composed of an alloy consisting of metal having the properties of nickel and cohalt, and a relatively small proportion 01 another metal more electroposltlve than nickel and having a refractory 96 oxld with a minimum melting polnt'ot about 1200* C.

2. An electric resistance element composed of an alloy consisting of metal having the properties of nickel and e0 halt, and a relatively small proportion otaluminlum.

3. An electric resistance element comprlslng'a strip, 100 strand or filament formed of an alloy ol' nlc kel'and s'lumlnlum.

' 4. An electric resistance element termed ots. metsl'sland desire to secure by Letters 90 and having a refractory oxld polnt ot about 1200 'C. V

5. An electric resistance element formed of a metal slloy consisting of nickel in the proportion ot'sbout elghtyeight per cent. ot the element ,chromlum in the proportion of about eight per cent. of the element and alumlnlum in the proportion o! sbout'tour per cent. of the element.

. ALBERT-L. MARSH. In presence otas. Iona-In,

LEW 

